(1) Field of the Invention
This invention relates to an active wire compensation circuit and a controller with the same, and more particularly relates to an active wire compensation circuit, which modulates the feedback signal by using a compensating current, and a controller with the same.
(2) Description of the Prior Art
FIG. 1 is a circuit diagram of a typical DC-to-DC buck converter. As shown, the DC-to-DC buck converter has a converting circuit 10, a controller 20, a load 30, and an output voltage detecting circuit 12. The output voltage detecting circuit 12 detects an output voltage Vo of the converting circuit 10 so as to generate an output voltage detecting signal Vfb. The controller 20 controls the operation of the converting circuit 10 according to the output voltage detecting signal Vfb such that the converting circuit 10 is capable to transform an input voltage Vin into the output voltage Vo maintained at a predetermined voltage level. However, since the output of the DC-to-DC buck converter is supplied to the load 30 through a wire 14 showing a parasitic resistor Rw, there must be some voltage loss Vw on the wire 14, which equals two times the parasitic resistor Rw times the current IL through the load 30. Thus, the load voltage Vo′ received by the load 30 would be lower than the output voltage Vo from the converting circuit 10.
To compensate the power loss on the wire 14, as shown in FIG. 2, a typical solution is to connect a detecting wire 16 between the output voltage detecting circuit 12 and the load 30 to remote sense the load voltage Vo′ for feedback control. That is, the detecting wire 16 is connected to the power supply end of the load 30 for executing feedback control. This method may compensate half the voltage loss on the wire 14, which equals the parasitic resistor Rw times the load current IL. However, the additional detecting wire 16 for remote sense increases the circuit cost. In addition, as the power transmission distance increases, the length of the detecting wire 16 must be extended.